箱梁腹板竖向预应力钢绞线和精轧螺纹钢筋的对比研究

通过对箱梁腹板竖向预应力钢绞线和精轧螺纹钢筋的对比试验，研究钢绞线和精轧螺纹钢筋竖向预应力规律，分析两种不同竖向预应力体系的特征和预应力损失，结果表明，钢绞线和精轧螺纹钢筋的第一次张拉预应力损失率和两者长期损失率基本相同，竖向预应力钢绞线的第二次张拉效果明显，预应力损失率较第一次张拉减小近1/2，对于控制主拉应力较大的高腹板的竖向预应力可靠度较大，反映了钢绞线作为竖向预应力筋的实际意义，为工程设计提供参考依据。

The Comparison Research of the Vertical Steel Wires and Wire in the Web of the Box-girder

Through the comparison assay about the vertical prestressed steel wires and wire in the web of the box-girder,we research the rules of the two vertical prestressed steels and analyse the features and the prestress loss of the two different vertical prestressed systems.The results indicate the first tension prestress percentage losses of the two steels are substantically the same and so like the long-term percentage losses,and the second tension effect of the vertical prestressed wires is obvious and the second tension percentage loss reduced to 1/2.For the high web with large tensile stress,the controlled vertical prestress has high reliability,which prove the practical significance by using the steel wires as the vertical prestressed wire and provide a reference for the engineering design.